mount

mount a file system
All files accessible in a Unix system are arranged in one big tree, the file
hierarchy, rooted at /. These files can be spread out over several devices.
The mount command serves to attach the file system found on some device to the
big file tree.
The system maintains a list of currently mounted file systems. If no arguments
are given to mount, this list is printed.

Syntax
mount [-adfruvw] [-t ufs | lfs | external_type]
mount [-dfruvw] special | node
mount [-dfruvw] [-o options] [-t ufs | lfs | external_type] special node
Options
-a All the filesystems described in fstab(5) are mounted. Excep-
tions are those marked as ``noauto'' or are excluded by the -t
flag (see below).
-d Causes everything to be done except for the actual system call.
This option is useful in conjunction with the -v flag to deter-
mine what the mount command is trying to do.
-f Forces the revocation of write access when trying to downgrade a
filesystem mount status from read-write to read-only.
-o Options are specified with a -o flag followed by a comma sepa-
rated string of options. The following options are available:
async All I/O to the file system should be done asynchronously.
This can be somewhat dangerous with respect to losing
data when faced with system crashes and power outages.
This is also the default. It can be avoided with the
noasync option.
force The same as -f; forces the revocation of write access
when trying to downgrade a filesystem mount status from
read-write to read-only.
noasync
This filesystem should not force all I/O to be written
asynchronously.
noauto This filesystem should be skipped when mount is run with
the -a flag.
nodev Do not interpret character or block special devices on
the file system. This option is useful for a server that
has file systems containing special devices for architec-
tures other than its own.
noexec Do not allow execution of any binaries on the mounted
file system. This option is useful for a server that has
file systems containing binaries for architectures other
than its own.
nosuid Do not allow set-user-identifier or set-group-identifier
bits to take effect.
rdonly The same as -r; mount the file system read-only (even the
super-user can not write it).
sync All I/O to the file system should be done synchronously.
update The same as -u; indicate that the status of an already
mounted file system should be changed.
union Causes the namespace at the mount point to appear as the
union of the mounted filesystem root and the existing
directory. Lookups will be done in the mounted filesys-
tem first. If those operations fail due to a non-exis-
tent file the underlying directory is then accessed. All
creates are done in the mounted filesystem.
Any additional options specific to a filesystem type that is not
one of the internally known types (see the -t option) can be
passed as a comma separated list; these options are distinguished
by a leading ``-'' (dash). Options that take a value are speci-
fied using the syntax -option=value. For example, the mount com-
mand:
mount -t hfs -o nosuid,-w,-m=755 /dev/disk2s9 /tmp
causes mount to execute the equivalent of:
/sbin/mount_hfs -o nosuid -w -m 755 /dev/disk2s9 /tmp
-r The file system is to be mounted read-only. Mount the file sys-
tem read-only (even the super-user can not write it). The same
as the ``rdonly'' argument to the -o option.
-tufs | lfs | externaltype
The argument following the -t is used to indicate the file system
type. The type ufs is the default. The -t option can be used to
indicate that the actions should only be taken on filesystems of
the specified type. More than one type can be specified in a
comma separated list. The list of filesystem types can be pre-
fixed with ``no'' to specify the filesystem types for which
action should not be taken. For example, the mount command:
mount -a -t nonfs,hfs
mounts all filesystems except those of type NFS and HFS.
If the type is not one of the internally known types, mount will
attempt to execute a program in /sbin/mount_XXX where XXX is
replaced by the type name. For example, nfs filesystems are
mounted by the program /sbin/mount_nfs.
-u The -u flag indicates that the status of an already mounted file
system should be changed. Any of the options discussed above
(the -o option) can be changed; also a file system can be changed
from read-only to read-write or vice versa. An attempt to change
from read-write to read-only will fail if any files on the
filesystem are currently open for writing unless the -f flag is
also specified. The set of options is determined by first
extracting the options for the file system from the fstab table,
then applying any options specified by the -o argument, and
finally applying the -r or -w option.
-v Verbose mode.
-w The file system object is to be read and write.
The options specific to NFS filesystems are described in the
mount_nfs(8) manual page.

The mount command calls the mount(2) system call to prepare and graft a special device or the remote node (rhost:path) on to the file system tree at the point node. If either special or node are not
provided, the appropriate information is taken from the fstab(5) file.

“The Ten Commandments and the Sermon on the Mount contain my religion” ~ John Adams